Enhancement effect of RuO2 doping on the reduction process of NOx by NH3 via V2O5-WO3/TiO2 particle catalyst under low-temperature: structure-activity relationship and reaction mechanism

•RuOx doping stimulates the high NH3-SCR activity of V2O5-WO3/TiO2 catalyst at low-temperature.•Doping of RuOx promotes the formation of more reactive monodentate nitrates on the surface of V2O5-WO3/TiO2.•The unique redox cycle and acid cycle matching mechanism consisting of monodentate nitrates and B acid sites on the RuO2-V2O5-WO3/TiO2 surface is formed through L-H mechanism.•RuOx doping accelerates the transfer of oxygen ions on the surface of V2O5-WO3/TiO2.